International Civil Aviation and Aircraft Noise
The jet engine allowed airplanes to both reach higher cruising speeds and carry more payload in comparison to traditionally powered airplanes. These advantages, however, had a high cost: aircraft noise, the most recognizable civil aviation pollution.
Aircraft noise adverse effects are not uniform around the world. The nuisance in the affected populations (sound pressure level, distribution of broadband frequencies, duration of noise) depends on many factors, among which are the following: type of aircraft and engines, the number of flights, flight trajectory (including takeoff and landing profiles), operational procedures (for example, adjustment of engine power), use and location of runways and operating hours, time of year and weather conditions.
The principle of a balanced approach to reduce aircraft noise was reaffirmed at the 36th ICAO Assembly in 2007. This principle, which aims maximum environmental benefit with the lowest possible cost, can be seen in detail in ICAO Doc 9829.
The balanced approach recommends four areas of action to deal with the issue of noise: reduction of noise at source, land-use planning and management, noise abatement operational procedures and the imposition of operating restrictions on aircraft.
Reduction of noise at source involves the development of new technologies for aircraft to meet the ICAO noise standards (Annex 16, Volume I), and the scheduling of a phasing out scheme to retire old and noisy airplanes.
During the last decades, aircraft and engine manufacturers made heavy investments in research and development of new technologies and have achieved great success in reducing the noise of jet engines. The latest airplanes are 50% quieter than the airplanes manufactured 20 years ago. Recent aircraft projects, like the Airbus 380 and the Boeing 787, are among the quietest airplanes ever constructed, and manufacturers are working to reduce noise even more in the future.
Air navigation service providers employ special operating procedures to reduce the noise impact on local communities around the airports. These procedures include the selection of flight paths avoiding the overflight of urban areas, diverting the exceeding traffic to uninhabited areas or reducing engine power shortly after take-off, among others. Certain changes in the design of the routes and the use of runways and approach and takeoff procedures can generate important reductions in the intensity of the noise nuisance and the number of the affected population.
In the field of operating restrictions, some States apply limitation of aircraft operations at airports based on environmental considerations, directly or through individual airport operators. Therefore, in extreme situations, operating restrictions are created for some specific types of aircraft at certain airports during the sensitive periods – in the evening or in the morning. Another action that qualifies as operating restriction is the adoption of curfews, i.e., the total closure of the airport during sensitive times, with the prohibition of operations during this period, except for emergency operations. As a negative side effect, the environmental parameters will decrease the designed operational capacity of the airport, reducing the use of the aeronautical infrastructure.
With respect to land-use planning and management, the balanced approach of ICAO adopts the premise that the construction and operation of airports generate a number of environmental impacts that could be minimized with prior planning and environmental management. The civil aviation authorities, taking into account the harmful effects of aircraft noise and the safety concerns associated to buildings in the immediate proximity of runways, establish restrictions on the use of soil around the airfields. In this sense, constructions and modifications of properties near the airports would need a prior official authorization.